Year	%
2000	48.8
2001	48.3
2002	47.4
2003	46.6
2004	46
2005	45.2
2006	43.7
2007	41.1
2008	40
2009	38.9
2010	38.6
2011	37.5
2012	37.5
2013	37
2014	35.6
2015	35.1
2016	34.2
2017	33.8
2018	33.7
2019	32.7